Process of manufacturing objects from asbestos.



R 684.032 I Ex I any) i e a v cow ADOliF W'UNSCHE, OF CHARLOTTENBURG, GERMANY, ASSIGNCR TO Sl EMEQNS & HALSKE ACTIENGESELLSOBAFT, OF BERLIN, GERMANY.

AS 52 eaoogss OF MANUFACTURING OBJECTS FROM ASBESTOS.

. l i SPECIFICATION forming part Of Letters Patent No. 684,992,553153111 October 8, 1901.

Application filed July 20, 1901. Serial No. 69,052. (No specimens.) I i To ail whom it 12mg concern: 1

Be it known that I, ADOLF WiJ'NsoHn, engineer, a subject of the German Emperor, residing at 2 Spandauerstrasse,Charlottenburg, near Berlin, Germany, have invented certain new and useful Improvements in Processes of Manufacturing Objects from Asbestos; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

In order to manufacture objects from asbestos fiber pulp or paste, a binding material must be used, since asbestos fibers cannot be felted like thoseofa'n-rmzt-o'rrzirby aid of materials are ill adapted, since the objectheat, water, and pressure. Hitherto glue, gum, starch, or other organic agglutinant or a solntionsoisolnble glass has been used for thispurpos; but if the object is to be used in contact with liquids such soluble binding swells and is finally disintegrated. This happens, for example, in the ease of asbestos plates manufactured with cementitious matter of the kind named when such plates are used as diaphragms in electrolytic apparatus. Soluble glass is equally insnflicient as a binding material for the purpose in question, whether it is used by itself or in conjunction with acids or salts which separate from it the silica it contains. The silica or silicic acid separated from soluble glass is by no means stable, being easily soluble in alkaline liquids. Besides, objects of asbestos made with aid of soluble glass lose considerably in porosity.

The present invention relates to the application of sihqgn tetrafiuorid as a WI uniting or fe tlng, as1 were, as estos fibe'rs. Objects manufactured with aid of this com; pound retain their original solidity in water and in aqueous solutions of salts and even in alkaline or feebly-acid solutions. Fo' this reason asbestos plates made with silicon tetraflnorid by this new process are particularly fitted for use as electmolytic diaphragms.

Whereas the older binding materials men; tioned above are added to the asbestos pulp before the objects'arefashioned, silicon tetrawater.

fluorid ma, be a bed 0 g ioned with aid of water and pressure alone after it has dried.

The mode of applying silicon tetrafluorid as an agglutinant for asbestos fibers is quite ditferent from that of applying the binding materials hitherto-used. Whereas the use of the latter depends on the separation of a sticky substance on drying, which sticks the fibers together without affecting their surface, the action of silicon finorid is a double decomposition with the chemical constituents of the asbestos-manic] y, silica, magnesia, and

I The surface of the asbestos fiber is etched. The water of hydration of. the as- 6 bestos forms silica with a part of the silicon contained in thesilicon tetrafluorid and hydrofluo c'd, To this silica isiid'dd' that arising from the decomposition oilbfi w mwilicato in the asbestos, and both am e, probably, with magnesia to form an acid silicate, which sticks together the surrm asbestos fiber where these are in contact. This may be regarded as a true felting, as the constituents of the fiber take part in the union. The hydrofluosilicic acidformed at the same time partly reacts with the magnesia liberated from the magnesium silicate, forming magnesium silieofiuorid, and partly'remains unchanged. The magne-' 8o siurn silico-fluorid and the hydrofiuosilicic acid may be separated from the mass by water or solution of alkali or may be converted in part into insoluble compounds. This 'action of silicon tetrafluorid on asbestos occurs, 8

even when the latter is dry, without the aid of any other agglutinant. It is only-necessary to submit the object which has been made merelyby pressing the fibers in a moist condition to the action of dry gaseous silicon e tetrafluorid. It is preferable, however, to use a solution of silicon fluorid, as it is then possible to, use a high or low concentration accordingly as the asbestos object is to be silicious in high or low degree. Obviously 5 the s'ilicontetrafluorid must be dissolved in e a medium which is anhydrous, or nearly so; otherwise the compound SiF will be decomposed, {Asa solvent for silicon tetratlnorid nearlyanhydrons alcohol is best suited. It

--"c0mpoun'dx The forwation of silica from the jects consisting in first vfashioning the object 15 Siliconfirzst occurs when the soliltionacts on and then submitting it}; "Jae action of silicon asbestos. The solvent used for dissolving fiuor'id. Y s the silicon tetrafluorid is separated from the 2. As a new article of mannfactnreasbes- 5 hardened object by heat and may be recovtos objects characterized by resistance towi;

ered by condensation of its vapor. v ter andohemical agents, and having their 20 The asbestos object loses hardly perceptifibers cemented together byaqtion of silicon bly I in porosity by treatment with silicon finorid. g fluorid, so that the process is particularly suit- In testimony whereof I have afiixcd my sig- 7 T'IO able for producing electrolytic diaphragms. nature iu presence of two witnesses. Having thus described the .nature of this 7 ADOLF WUNSCHE.

invention and the best means I know of car- Witnesses: rylng the same into practical eifect, I claim- I HENRY HASPER,

turing asbestos ob- WOLDEMAR HAUPT.

1. Aprocess for manufac No refere ce 5 

